1. Field of the Invention
This invention relates to microprocessors. In particular, the invention relates to audio control.
2. Description of Related Art
Audio functionalities have been increasingly incorporated in modern microprocessor systems. Advanced features in audio systems such as stereo full duplex codec and three-dimensional stereo enhancement typically found in home entertainment systems can now be included in a personal computer (PC).
To accommodate the increasing demand for audio processing, especially in the digital domain, the computer industry is standardizing audio components with advanced features. One such standard is the Audio Codec ""97 as documented in the Audio Codec ""97 Component Specification Revision 1.02, dated May 28, 1996, published by Intel Corporation (xe2x80x9cAC ""97 Specificationxe2x80x9d).
The AC ""97 is an analog input/ output (I/O) component of a two-chip PC audio solution. The AC ""97 analog component performs fixed 48K sample rate digital-to-analog and analog-to-digital conversions (DAC and ADC), mixing, and analog processing (e.g., tone, 3D stereo enhancement). The AC ""97 typically serves as a slave to an AC ""97 digital controller.
The AC ""97 digital controller is interfaced to the AC ""97 analog component through a standardized AC-link digital serial interface protocol as specified in the AC ""97 Specification. The audio subsystem may include a number of audio channels. A digital audio controller controls these audio channels by sending and receiving digital data streams at pre-defined time slots in a serial data link.
Traditional techniques to implement the digital audio controller include a fixed set of logic circuits serving a fixed set of audio channels. This approach has a number of disadvantages. First, the amount of hardware in the digital audio controller is excessive to accommodate all the available channels, even when only a few of the channels are actually being used. Second, the software driver in the host processor tends to be inflexible and requires updates when the system is targeted to different applications and/or platforms.
Therefore, there is a need to have an audio controller that provides flexible control functionalities efficiently with less hardware.
The present invention relates to a method and apparatus to control audio channels. The apparatus comprises a plurality of configuration registers and a corresponding plurality of channel logic circuits. The configuration registers configure usage of the audio channels. Coupled to the configuration registers, the channel logic circuits provide logic functions to the audio channels according to the configured usage.